Ichthyomyzon Gagei - Ecology

Ecology

The diet of I. gagei changes as it undergoes metamorphosis during its life cycle from one phase to the next. The diet of larval I. gagei consists mainly of organic detritus. Studies that focused on closely related lamprey species (I. fossor) found that the stomach contents of larval lampreys contained 97.9% organic detritus, 2.12% algae, and 0.09% bacteria (Bowen 1994). After metamorphosis into the adult phase, southern brook lampreys do not feed but rely on stored fat reserves accumulated during the larval stage for energy and nutrients. Studies have found that the digestive tract of the southern brook lamprey actually shrinks and becomes functionally useless as larval lampreys enter the adult stage. I. gagei encounters a wide range of predators in its natural habitat (Gallaway 1977). The eggs of adult lampreys are preyed on by various species of fish and crayfish (Renaud 1997). Southern brook lampreys in the larval stage serve as prey for a wide range of fish and bird species (Renaud 1997). Adult forms of the Southern brook lamprey are preyed upon by larger fish species such as the Northern pike (E. lucius), perch species, the European chub (S. cephalus), and the mudpuppy (N. maculosus). I. gagei shares similar habitats and resources with many species of shiners (Notropis), the longnose dace (Rhinichthys cataractae), Johnny darters (Etheostoma nigrum), and mottled sculpins (Cottus bairdi) (2012. Minnesota Department of Natural Resources). I. gagei fills a very specific niche in the river systems that it occupies. Any daramtic increase in predators or decrease in food availability may result in a decline in the number of I. gagei found in these systems.